Treatment of hydrocarbon oils



Patented'Dec. 26, 1933 6 UNITED STATES 1,940,726 TREATMENT OFHYDROCARBQN OILS Jacque C. MorrelL'Chicago, 111., assignor to 'UniversalOil Products Company, Chicago, 111., a j corporation of South Dakota NoDrawing. ApplicationJanuary 8, 1931 Serial N- 507,519

8 Claims. (Cl. 196 -24) This invention relatesto the treatment ofhydrocarbon oils, and refers more particularly to the treatment of thelighter'distillates produced in the cracking of heavy hydrocarbons.

More specifically the invention contemplates the treatmentof crackeddistillates with chemical reagents of a particular nature effective inimproving the quality of the distillates as regards their adaptabilityto commercial uses, particularly as fuels for internal combustionengines.

The chemical nature of the lighter hydrocar' bon fractions produced bythe cracking of heavy hydrocarbons under elevated temperatures andpressures is very complex. Representatives of practically allhydrocarbon groups have been identified, such groups being, for example,parafiins, olefines, naphthenes, aromatics, terpenes, et cetera.As-charging oils frequently contain-minor amounts of sulfur, oxygen andnitrogen derivatives of hydrocarbons, the cracked products contain theseelements in compounds of altered type due to rearrangements andreadjustments during the cracking and subsequent reconversion period.The sulphur originally held in combination in the raw chargingstocks'appears as hydrogen sulfide and in such sulfur containinghydrocarbon derivatives as mercaptans, sulfides or sulfur ether,thiophenes, et cetera. Frequently, when the raw cracked distillates aretreated with acid or alkaline reagents, such as sulfuric acid or causticsoda, further rearrangements occur, producing compounds of a hybridnature such as the sulfoxy derivatives. It may be stated generally thatthe presence of sulfur and/or oxygen compounds is undesirable because oftheir tendency to render the distillates malodorous and unstable in thepresence of polymerizing influences so that frequently the oils go offcolor and develop gummy or resinous substances during storage. Thepresent invention is concerned with improvements in methods for removingor altering the sulfur compounds in cracked distillates so as to renderthem either less objectionable from a standpoint of odor and instabilityor of removing them to a degree required by'oommercial requirements.

In one specific embodiment of the invention, cracked hydrocarbondistillates are treated with preferably alkaline alcoholic solutions ofsulfides, hydrosulfides and polysulfides of the alkali and/ or akalineearth metals. While the treatment is preferably used as an adjunct toother treatments, in some cases it may constitute the only treatmentnecessary. Y

The various sulfides, hydrosulfides and polysulfides of the metals ofthe groups mentioned vary in their solubility in absolute or anhydrousalcohols, such as ethyl or methyl alcohols, the

. solubility usually increasing as the alcohols are alkali. By properselection of the'base metal, the

particular sulfide thereof, the strength of alcohol and the free alkaliconcentration, a wide range of reagents may-be prepared applicable tothe treatment of cracked distillates.

Treating reagents prepared as mentioned are particularly effective inremoving or altering certain types of sulfur derivatives ofhydrocarbons,

the apparent mechanism of the reaction being the polymerizing orcondensing of the organic sulfur compounds with the metal sulfides whichforms either insoluble precipitates or solublehighboiling compoundswhich remain behind upon distillation of the lighter fractions of theoils treated. In some instances the compounds formed may be soluble inthe reagent and in other cases precipitates may appear which are removedby sedimentation or other means.

Reagents of the type comprised in the present invention are particularlyefficacious when used following treatment of cracked distillates withsodium plumbite solutions. The use of sodium pluinbite forms primarilymercaptides of lead which are more or less soluble in the oils. Theaddition of powdered sulfur, such as flowers of sulfur, to oilscontaining the lead mercaptides 1 5 causes what is known as a break inthe treatment which is really the precipitation of the black leadsulfide, the organic residues combining to formcompounds of the type ofdisulfides. When sufiicient care is not exercised to avoid 1 0 addingexcess of sulfur over that necessary to cause the break a portion of theexcess remains dissolved in the oil and apparently oxidizes when the oilis exposed to light and air, causing the a better controlled addition ofthe amount of sulfur requisite to cause precipitation of the lead assulfide, assures maximum contact due to easier miscibility andapparently removes some of the sulfides, thus lessening the amount ofsulfur left in the oils from both standpoints.

In treating oils with reagents characteristic of the inventionoperations may be conducted in various types of equipment and in avariety of ways, for example, the oil may be treated in a batch agitatorby circulating from the bottom of the cone back into the top throughdistributing means by means of a circulating pump, the reagent beingadded to the suction side of the pump and being mixed during passagetherethrough and through the nozzles or atomizing means on the dischargeside. Reagents may be injected at suitable points in the travel of oilsthrough continuous treating equipment, consisting of mixing devices ofvarious types followed by set,- tling and washing chambers. In someinstances relatively strong solutions may be added to oils undergoingdistillation with fire and/or steam with retention of desirablecompounds in the still residues. In other instances treatment underconsiderably elevated temperatures and pressures may be advisable, inwhich case apparatus of requisite strength must be employed.

The foregoing description of the invention has disclosed reagents andmethods of operation which are comprised within the scope of the process of the invention, but these have been given for illustrativepurposes only and are not to b considered in a limiting sense.

As an example of the results obtainable by the operation of the processof the invention, a

cracked distillate containing 0.35% total sulfur in various forms ofcombination may be treated with 5% by volume of a solution of apotassium polysulfide in 50% ethyl alcohol containing 5% free alkali,treatment being conducted at ordinary temperatures and pressures bycirculating from and back to a batch agitator. After suitablesupplementary water-washing, it may be found that the sulfur content ofthe distillate has been reduced to 0.2%. If such a treatment isfollowed, or in some cases preceded, by supplementary treatment withminimum amounts of 66 B. sulfuric acid, the sulfur content may be foundreduced to approximately 0.08%.

I claim as my invention:

1. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alcoholic solution of a sulfideof an alkali metal.

2. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alcoholic solution of a sulfideof an alkali metal at substantially atmospheric temperature.

3. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alcoholic solution of apolysulfide of an alkali metal.

4. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alcoholic solution of a sulfideof an alkaline earth metal.

5. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alkaline alcoholic solution ofa sulfidev of an alkali metal.

6. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alkaline alcoholic solution ofa polysulfide of an alkali metal.

7. A step in a process of desulphurizing the condensed overhead productresulting from the cracking of hydrocarbon oil, which comprisessubjecting said oil to treatment with an alkaline alcoholic solution ofa sulfide of an alkaline earth metal.

8. A process for refining hydrocarbon oils con taining mercaptans whichcomprises treating the oil first with plumbite solution and then with analcoholic solution of a sulphide of an alkalinous metal.

JACQUE C. MORRELL.

